3-6. Conductors in Static Electric Field Conductors contain free charges. Inside: No charge is inside a conductor No field is inside a conductor. A conductor is an equal-potential body. Boundary conditions at a conductor to free space interface EEE340 Lecture 12

Example 3-11. Conductor shell with a point charge at the center Example 3-11. Conductor shell with a point charge at the center. Find the and V. Solution Gaussian surface S1 i. e. The potential EEE340 Lecture 12

Inside a conductor. Gaussian surface S2 Note V2 is constant since conductor is an equal potential body. Inside a conductor. -Q induced on the inner and +Q on the outer surface of the shell. EEE340 Lecture 12

The integration constant K is found by Gaussian surface S3 The potential The integration constant K is found by Namely Therefore EEE340 Lecture 12

3-7. Dielectrics in static E-field Ideal dielectrics do not contain free charges They contain bound (polarized) charges Dielectrics in static E-field produce the induced electric dipoles. 3-7.1. Equivalent charge distributions of polarized dielectrics Polarization vector Volume density of electric dipole moment. EEE340 Lecture 12

Potential due to the polarized dielectric Where It can be shown The total charge EEE340 Lecture 12

3-8. Electric flux density and dielectric constant Where the electric flux density (displacement) Electric susceptibility Relative permittivity (dielectric constant) Absolute permittivity EEE340 Lecture 12